Concentrated beam light



Aug. 9, 1932. H, UEL 1,870,671

CONGENTRATED BEAM LIGHT Filed May 2. 1927 5 Sheets-Sheet l a f g m b c d e v k l INVENTOR jyz'lllwwsefluel;

ATTORNEYS Aug. 9, 1932. H. BUEL 1,870,671

CONCENTRATED BEAM LIGHT Filed May 2. 1927 3 Sheets-Sheet 2 INVENTOR Aug. 9, 1932. 'H. BUEL 1,870,671

CONCENTRATED BEAM LIGHT Filed May 2, 1927 5 Sheets-Sheet 3 Patented A11 9, 1932 UNlTliZB g'l ryi hfi EATENT OFFICE HxLLno-Us-n or new YORK, n. Y., nssIeNon, BY MESNE. ASSIGNMENTS, or ONE- nriLr TO LILLIAN LOUISE HAMMQND AND WILLIAM P. HAMMOND, JR.

CONCENTRATED BEAM LIGHT Application filed May 2,

This invention relates to improvements in concentrated light beam illumination, such as headlights for vehicles, searchlights or other uses.

One of the objects of his invention is to provide primary reflector means whereby rays reflected from points on the reflector farthest from the light source are projected at. greater divergence from the principal axis. than rays reflected from points on the said reflector nearer the light source, which is. located substantially at an assumed focal point.

Another object of this invention is to provide, means to offset and correct tolerance effects caused by imperfections and defects occurring in light bulbs, light sources, sockets, sleeves and reflected surfaces, which cause objectionable defects of light rays from the theoretical or normal course.

Another object of this invention is to provide a method of concentrated light beam illumination, which allows more complete and accurate control of all light rays, andv which will permit a greater predetermined allocation of substantially all of the light by modifying and correcting divergences in the rays forming the light beam.

Another object of this invention is to pro vide a primary reflector having a particular fornrgenerated by an arbltrary decrement, which will permit the accurate placement of all the rays from the filamentsource to the final object without glare and whereby the rays. nost sensitive to deviaaions in the reflector surfaces and to errors and tolerances in the filament construction, will be so positioned that they can not come within the range of an observer in front of the vehicle, and whereby the rays reflected from the pertions of the reflector less sensitive and less final beam when the light source is placed on the vehicle.

Another object of this invention, as compared with the usualparabolic reflector, is.

to so construct the reflector surfaces behind the parametric plane that the surfaces behind 1927. Serial No. 188,317.

the parametric plane are not substantially more sensitive to tolerances and defects, than surfaces on. the parametric plane, and the: rays from such portions of the reflector may be directed substantially parallel to the horizontal axis of the headlight.

. Other and more detailed objects ofthis invention will appear from thefollowing de scription thereof, takenin conjunction, with the attached drawings, illustrating thepreferred forms of. embodiment of my device and in which Figures 1, 2, and 3 illustrate diagrammati cally basic forms of the various curves used in my reflectors.

Figure 4 is a center section thru, a completed. reflector, showingin detail the construction of. the five different portions of the complete reflector.

Figure 5 is an enlarged-central section of the reflectors showing the paths of certain of the rays therefrom.

Figures 6 and 'Z' are similar toF-igure 4, showing modified forms of primary and sec ondary reflectors.

' Figures 8 and 9 are respectively the plan and cross sectional views of the secondary reflector, shown iii-Figure 4.

FigureslO and 11 are respectively the plan and cross sectional view of the secondary reflector shown in Figure 6.

FigurelQ is a vertical cross section of my improved headlight.

Figure 13 is a diagrammatic showing'of my dual headlight.

It is to be notedthat my headlight may comprise threeprincipal parts, the primary reflector which is formedby the-revolution of a generated curve about a right line, asecondary reflector adjacent thereto which has an irregular surface specifically plotted and that part of the primary reflector below aperpendicular plane thru a reference point in the ax s, which is the parametric plane, and which may have any one of severalforms.

I have discovered when the curvature of a reflector surface is generated by taking-as the factors some coefficient ofthe gradiently decreasing angles formed by the side of the cones of: rays, as the successive assumedreflecting points recede from an assumed reference point, comparative with the focal point of a parabolic reflector, which coei'fi-- cient may be a constant but which is preferably a variant coeflicient, and where such factors are cumulative, that it is possible to get far better and very much more flexible control and allocation of the rays and light flux than is possible with a paraboloidal reflector or any regular modification of a paraboloid or any surface generated upon any regular factor or line comparative with the directrix of a parabola.

I have also discovered that the objectionable eifects of tolerances in light bulbs and socketsv and defects in reflecting surfaces as elements of objectionable glare in the usual parabolic form of headlight reflectors, due to the proximity of the reflecting surfaces between the parameter and the heel of the reflector to the light source, may be largely eliminated by makin all or a portion of this part of the reflecting surfaces concentric upon the assumed reference point with aradius substantially equal to the radius at the parameter, or part concentric and, part shaped in a manner similar to the portion between the parameter and the rim of the reflector, with the distance from the assumed reference point maintained substantially equal to that of the concentric portion. This manner of shaping this part of the reflector will also result in reducing the diameter of the light beam to about one half that of the usual parabolic reflector of comparative dimensions and thereby greatly increases the condensation of the light flux in an area approximately one fourth that of the paraboloid.

In Figures 1, 2 and 3, I have illustrated three forms of curves and the particular resulting cones of rays from each. Figure 1 may be arbitrarily termed the plus or incre ment curve which indicates that the change of curvature is brought about by theaddition'of successive increments to a variable angle, which is the tanget angle of a parabola, the increments being small and it may be a variable percentage of the angle between the sides of the cone of rays at the point considered. The effect of this addition of increments to form the plus or increment curve may best be illustrated by taking some point, such as the point 10 on the primary reflector and which is a known distance from the assumed reference point F. It willbe noted that the cone of rays F -10F is formed because of the finite size of the filament. The reflection from the reflector point 10 is the cone of rays R10R. If the tangent to the reflector surface at the point 10 was the same as the tangent to a paraboloidal reflector at a similar point, the center line of the .ray would'be parallel to the axis thru the focus.

In view of the fact however, that a positive percentage increment has been added to the tangent at such point of surface, the ray F10 is reflected along the line 1 OR at an angle to the axis.

The point 11 shows in more exaggerated form, the same condition in which the outer rays of the cone of rays from this point, rays R and R are at a greater angle from the axis than the rays R and B. This is be cause the increments are so cumulative as to increase the tangent of the reflector at the point a greater amount at the points farther out from the filament.

Comparing this curve with the curve of an ordinary parabola as shown in Figure 2, it is found that every point of my curve, beginning at the reference plane and moving progressively outwardly, is nearer to a line corresponding to the directrix than to a reference point corresponding to the common focus. The progressive decrement, being a cumulative factor successively of the angles formed between the two sides of the several respective cones of rays reflected from the sequential points assumed to form such curve, the curve formed will be continuous but not normally of any regular increment of curvature. Preferably it will be of irregular increment of curvature, variable at will to meet the assumed requirements, and the cones of rays reflected from such sequential points and points intermediate may be definitely controlled in a desired manner assumed for them so that the light flux may be condensed or diffused on any assumed areas to be illuminated. In this form of the curve, points on the reflector surface farthest from the assumed reference point will reflect cones of rays, so that rays in the middle of the cones of rays are projected at greater angles away from the principal axis than the middle of a cone of rays reflected from points nearer to the assumed reference point. TheoreticaL ly, in the parabolic section shown in Figure 2, the centers of the cones of rays are parallel to the central axis through the focus.

In Figure 3, I have illustrated a portion of a curve which may be arbitrarily termed the minus or decrement curve. The. middle ray of the cone of rays at the point 13, which is nearer to the filament, not shown, is at an inclining angle to the line of the principal axis thru the reference point, which in the paraboloid would be termed the axis and this ray is not only at an angle to the axis but is at the opposite angle to the cone rays at the point 10 on the plus or increment curve. From the point 12 at a greater distance from the reference point, the middle ray of the cone of rays is at a greater angle to the so-called axis, which angle is opposite that of the cone of rays from the point 11, in View of the fact thateumulative decrement is taken from the tangent to the ray at that point.

may be considered to be. dividedintofivesec:

tions, section 1 of which is that portion of the primary reflector; above the parametric plane. The side of this reflector is the same asthe curve shown in Figure 1, and is merely asurface of revolution about a right line thruthe reference point. i

The second section is. concentric about the reference point, the radiusbeing not substan: tially less than and preferably equal to the distance fromthe reference point to the primaryreflector curve on the parametric plane, which is shown as the distance F P0. This 25 portion is limited by a line drawn from the lip of the reflector thru a point, which is the maximum position to which the filament may extend within the limits of guaranteed tolerance. With the usnalconstruction, and with present standards, this point will be of an inch above the predetermined reference point F. The intersection of the line from the lip ,thru this maximum position with the are forming the lower extremity of this portion 2 is the location of the point C.

tion having but suflicient pitehin its side so thatthe reflector may be withdrawn from a suitable mold. The diameter at the top is 40.; equal to the diameter at the point C and the diameter at the point D is onlya fraction less, the angle being of the nature of a few degrees from a true cylinder.

Section4 which adjoins section 3 is parabe 5 -oloidal so that substantially allofthe rays are projected parallelto the axis, It is to be noted however, that a, substantial portion mined as thecritical points, so that therays willbe directed from the secondary reflector to assumedpoints in the roadway. In View of the fact that the directionof all-therays, 1 mm he primary eflector re alculatedand:

Section 3 is a substantially cylindrical sec- The section which is the secondary reflector are known it is, obViousthat b-yfcorrectly forming the surfaces of. the secondary re flector, therays may be. directed tov any; Clflr'; sired position.

Illustrated in Figure 5 is the diagrammatic:

relation of the convergent or minus curve primary reflector with the compound base and the secondary reflector of the form shown inFigure 4. Ashas been explainedtherays emanating from the sourceF will bein the. form of a cone, inasmuch as-the sourcehasa finite size. This isparticularly illustratedin Figure 1. It is to be noted, howeverthat only certain portions of the cone require particular consideration, as for example, in Figure 1-, the side of the ray 10R is the more critical because when redirected by a secondary reflector, it will be that portionof the ray cone which would tend togo abo'vea horizontal lineand therefore causeglarein an oncoming drivers eye. Itis therefore. the. more critical side of the ray, which must. be taken care ofprimarily in designing and, plotting the secondary reflecton Similarly on the other side of the reflector as shown in Figure 5, the opposite side of the coneof: rays would be the more critical. Ineach case it is the forwardside of the cone of rays.

The detail manner. of constructing the pri.-. mary reflector after assumingthevalues of a. filament of the usual size anda distance; between the focus and the intersection of the, parametric plane with the principal curve at;

the point P0, which for purpose of example.

is here indicated as two inches, is to determine the angle of each cone of rays for eacl-r tor. The typical example ofthis. is shown in Figure 1, where the cone angle is the angle F;1OVF.

point on the reflector from the reference point, which on the primarypointBo istwo;

inches and knowing the size of the lightment audits tolerance, which is a definite;

amount, depending upon the. light, the. cone: angle, of cone of rays at that pointcanbe; readily determined. Fromjthis; it; can be.- de;

termined whatits subsequent direction .is by determining the tangent: angle. of thereflecs tor at that point.

For the next points, the distance a, point on a comparative paraboloid havinga focal length of one inch, the distance of which points are known, was used; /8"! Vela, tical increments, were set: ofif'from the, para,

metric plane up towardv the lip of the reflector to determine the comparative -point on;-

the generated curve. The tangentg angle, will then be determined for each. ofthe.

pointsat intervals, which fonthisparr ticular illustration, embmces 24 points Knowing the distance. of the,

Thethird determination was to add to the tangent an le at the point in consideration, an'accumu lative factor, which was k the cumulative percentage increment of the cones of rays, only of the correction bein added to the tangent to cause the requlred degree of change to be imparted to the critical rays of the cones of rays.

For example, the distance to P from the reference point being two inches, the filament 'size being 2 mm., the first'ray angle is approximately 134 minutes. Atthe next vertical increment the distance to the reference int changes slightly and the ray angle was etermined to'be 118 minutes. The first tangent angle is 45 degrees and this is plotted for the distance necessary to intersect the vertical line at the vertical increment in height which is inch. This determines the second point. But here, the tangent angle was found to be 43 degrees 19 minutes and to this is added of per cent of 134 minutes or 6.7 minutes making a corrected tangent an 1e of 43 degrees 25.7 minutes and this was p otted until the next vertical interval was intercepted. For the third point, the tangent angle was 41 degrees 48 minutes and the accumulative factor was ten per cent of the first ray or zero plus ten per cent of the second ray or 13.4 minutes plus ten per cent of the third point-or 11.8 minutes. The

I total accumulative factor is thus 25.2 minutes andthe corrected tangent angle is thus 41 degrees 48 minutes plus of the'accumulated factor of 25.2 minutes or 42 degrees .06 minutes. 1

As the points progress the cumulative factor also increases and while the tangent angle decreases yet as compared with the corre- ,s nding tangent of a parabola it increases. en the curve plotted is the one shown in Fi re 3, this is changed and as compared wit the parabola, the tangent angle decreases with a cumulative decrement. It is obvious that the accuracy of the points depends entirely upon the required accuracy of the light.

and the above calculations and assumptions are only given for purposes of example, and only generally correspond with the highly exact computations made, but which would not additionally clarify this example.

The generation of this curve might also be described in terms of increments added to or deducted from the angles which the tangents at the successive points in the curve make with the principal axis.

Starting with a tangent at 45 to the axis at a point in the parametric plane, the location of the successive points and tangents thereto may be determined by triangulation,

using angles which the factors make with the rinclpal axis as the reference, deducting b othe difference between a right angle and the angle which the outer ray of a cone of rays,

3 having the light source as its base and the reference point sought as the apex makes with the axis and by adding or deducting of the assumed percentage of the angle found between the sides of the cone of rays at such point and the cumulative increments of 5 the assumed precentages of the cones of rays for the preceding successive points similarly determined in generating such curve.

For example to find the angle with AA to be given to the tangent at P starting with a tangent at P at an angle of 45 to the axis A A, point P in the first plane of a uniformly spaced series of planes perpendicular to the axis through the points M to M inclusive; produce tangent at P to intersect the plane through M at P erect P A parallel to the axis; P F, M 1 and M A are known; angle A P P equals tangent angle with the axis at P A P is found and M P is then known; angle P FP is found and angle F P F is found, which is the angle between the sides of the cones of ra s at P Then the angle of the tangent with the axis at P will be afinlimw 2 v 2 =tangent at P curvature the arc P P is described for that section of the curve. In a similar manner the successive points are located and tangent angles with the axis determined and the curve P P is generated. The revolution of this curve about the axis will produce the surface of zone 1.

As shown in Figure 5, a number of critical or determinative points have been selected and the direction of the rays from these points illustrated. For example, the point, PH is selected on the primary reflector 1 of the ray angle from the filament F reflected to the secondary reflector 5 is again reflected from the point SH from the light and at such an angle that this ray'is substantially parallel to the horizontal axis and thus goes to the AH area.

Similarly with the other AH; PA, SA, AA; PC, S AC; from the other portion of the secondary other points have been selected, PP, PM, PQ; PS, PN PL. From these points the rays from the focal point F are reflected to the secondary reflector at the points SP, SM, SQ; SS, SN, SL;. from which the light is again reflected to the areas AP, AM, AQ, AS, AN, AN, AN, AN' AL. A further point PB on the base 4 of the reflector is similarly selected and the critical light ray is again reflected from the point SB on the secondary reflector to the area AB.

oints PH SH,

The selection of these points while not ma terial to this invention have been chosen by reference to certain arbitrary standards of Illuminating Engineering Societies which refer to the A point, B point, C point, etc., and which correspond with certain distances in front of a vehicle having a light spaced a certain distance above the ground. These particular areas have been chosen and definite amounts of light have been estimated for these points as being the minimum amount necessary and for purpose of examplethese areas may be used in determining the curvature of the reflector surfaces.

In order to construct this portion of the reflector, the curve is revolved on the principal axis, thus making the proper shape. The limit to which the vertical increments are taken depends entirely upon the size of reflector unit desired. However, with the two inch minimum distance, the vertical height of this portion will be nearly three inches with final opening of approximately 7 inches in diameter.

As has before been mentionedthe secondary reflector is plotted in this instance by proj ecting the rays upward from the plotted points ofthe primary and with the knowledge of their actual angle with the principal axis.

In. the modification of this reflector as shown in Figure 6, it will be notedthat the secondary reflector is provided with a supplemental section 6a, which is illustrated in greater detail in Figures 10 and 11. The use of such a section aids the construction of the secondary reflector, so that the proper light is more effectively proportioned on the road in front of the vehicle. It will be noted however, that the section'Ta of the reflector outside of the raised section 6a is of the common shape as shown in Figure 4, in order that the light maybe properly distributed at the sides ofthe road. In this modification, it will also .be noted that section 3 has been eliminated from the combined primary reflector and the paraboloidal section l immediately ad olns Figures 4i and 7, and particularly as shown:

,in Figures 8 and 9 is modified to the extent of showingthe corrugations or striations 15,

which aid in diffusing the light so that adjoining cones of rays will more effectively intermingle andjgivea complete graded light, the shape of the secondary reflector 5 in Figuret is shown in Figure 8 a-nd'ifsections are taken transverse on the lines a, b, c, d, e, and f, the resulting curvature will be as shown in Figure 9. Similarly the surface of the secondary reflector 564 shown in Figure 6 is illustrated in Figure 10 which also shows the projecting portion 6a. if in this figure, sections are taken on the lines 9, h, 2', j, is, Z, and m, the resulting curvature will be as shown in Figure 11.

In Figure 12, I have shown a complete lamp, comprising in general the reflector shown in Figure 4. The principal parts are the upper primary reflector 1, the concentric portion 2, cylindrical sections 3 and a parabo loidal base not shown, the secondary reflector or section 5, the light source F and the shell 25. The secondary reflector is pivotally attached at 26 to facilitate adjustment by the screw 27, when the light is attached on the vehicle. The light unit F may also be adjusted to focus by means of the adjusting screw 28. In order to permit a strong illumination of objects relatively close, but at the sides of the vehicle, an opening 29 is provided in the side of the lamp which may be provided with suitable glass. The front is also protected by preferably clear glass 30. In view of the careful construction of the secondary reflector 5, it is substantially essential that a clear glass be used, as heretofore all of the rays have been treated and properly positionedto the respective locations on the ground in front of the vehicle and found desirable.

A duplex lamp shown in Figure 13 can be constructed from primary reflectors 7 and 8 abutting each other at the section thru the focus. These primary reflectors whichare preferably of increment or decrement curve construction as shown in either Figures 1 or 3, may be extended any distance as desired and are adapted to be of such size that but one light projector would be used on the automobile and would have the principal axis of the light rays from the secondary reflector at such a distance apart as would be necessary. The direction of the rays is shown from the filament F by the dotted line, and the second-' ary reflector surfaces are indicated by the curves 7a and 8a respectively. These surfaces may be similar to the section 5 in that they are continuous curves without projections as shown in Figure 6 but in view of the adj oining primary reflector surfaces these curves mustbe suitably plotted in accordance with the method as outlined in connection with Figure 5.

In conclusion my invention consists principally in the direction and redirection of light rays from a definite filament which takes into account the errors in the position, size and shape thereof, together with the errors in the construction of the reflectors by the use of a generated reflector surface and which takes into account the critical position of the rays so that the more dlfli'cult controlled rays are placed in such position in the final beam, that usual tolerance will not cause those particular cones of rays to seriously affect or alter the final light beam and the less sensitive reflector portions and the more easily controlled rays are placed in that part of the beam in which the greatest objection would be had, if the rays were seriously misplaced. It is to be understood that the surface generated is generated preferably by subtracting a proportionate part of the tangent angle at any assumed points of the reflector, which decrement is cumulative so that a greater concentration or diffusion may be had at will, and so that the critical portions of the rays are most effectively reflected from the primary reflector and so that the final correction can be made in the secondary reflector. It is to be further understood that the portion of the reflector below the parametric plane is preferably not substantially closer and the surfaces therefore are not more sensitive than the point on the primary reflector immediately at the parametric plane. By such construction, it is thereby possible to obtain a greater concentration or diffusion of the light, taking into account the errors in design tolerance and variations of the elements and if possible to give more complete and accurate controlof all the light and to distribute it in front of the light projector in predetermined amount, so that uniform illumination without glare can be obtained.

, While I have described several forms of the embodiments of this invention, it is to be understood that I do not desire to be limited to mfy' particular forms of construction or theory 0 operation except as hereafter specifically claimed.

I claim: 7 1. In a headlight of the class described, in combination, a light source and a primary reflector adapted to reflect light therefrom,

said primary reflector being a surface of revolution, the curve of which is irregular and is generated by adding to the tangent angle'of a comparative parabola at points starting from the parametric plane and progressing outwardly, a progressive increment which is cumulative of all the preceding increments, such increments being the assumed percentage of the angles formed between t e sides of the cones of'rays for such points. 1

2. In a headlight of the class described, in combination a light source and a reflector adapted to reflect light'therefrom, said reflector being a surface of revolution, the curve of which is irregular and is generated by deducting from the tangent angle of a comparative parabola at points starting from the parametric plane,and progressing outwardly, a progressive increment which is cumulative of all the preceeding increments, such increments being the assumed percentages of the angles formed between the sides of the cones of rays for such points.

. 3. In a headlight of the class described, in combination, a light source and a primary reflector adapted to reflect light therefrom, said primary reflector being a surface of revolution the curve of which is irregular and is generated by progressively varying in one direction the tangent angle of a comparative parabola at points starting from the parametric plane and progressing outwardly, each progressive variation being cumulative of all the preceding variations, such variations being the assumed percentage of the angles formed between the sides of the cones ofrays for such points.

4. In a headlight of the class described, in combination, a light source and a primary reflector adapted to reflect light therefrom, said primary reflector being a surface of revolution, the curve of which is irregular and is generated by progressively varying in one direction the tangent angle of a comparative open conic section curve at points starting from the focal plane and progressing outwardly, each progressive variation being cumulative of all the preceding variations,

such variations being the assumed per-- centage of the angles formed between the sides of the cones of rays for such points.

5. In a headlight of the class described, in combination, a light source and a reflector adapted to reflect light therefrom, said regrees to the axis of the primary reflector, the

surface of said secondary reflector starting at its inner end substantially in contact with the rim of the primary reflector, having a curve generated progressively outward, so that the angle which the tangent at each successive point makes with a plane through the axis of the primary reflector perpendicular to the forwardly horizontal axis of the headlamp will vary from forty-five degrees by an amount equal to of the angle which the forward ray of a cone of rays reflected by the primary reflector makes with said plane less of the angle to the horizontal axis of the headlamp assumed for the direction to be given to such ray when reflected by such point on the secondary reflector and to thereby assure that no ray of any cone of rays re flec ted by the primary reflector onto the secondary reflector, on reflection by the secondary reflector, will have an angular direction rising above the horizontal plane of the headlamp.

In testimony whereof I have affixed my signature to this specification.

HILLHOUSE BUEL. 

